1. Field of the Invention
The present invention relates to a covering, and more particularly to a covering of a building's opening.
2. Description of the Related Art
A covering for an opening of a building, such as sashes for a window or doors for an entrance, has various types. Take a window covering for example, the common type window covering has two sliding or hinged sashes. In this type of window covering, the sashes take some space of the window. It is bad for ventilation.
Another type of window covering is similar to a casement window, having two hinged sashes, one of which is pivoted on the frame, and the other one of which is slidably engaged with a rail.
Move the sliding sash will fold the sashes, and the folded sashes are vertical to the rail. It provides a large window opening when a user opens the sashes.
However, people may run into the vertical sashes accidently when the sashes are opened. An improved window covering provides a warp rail, with which a user may move the folded sashes off the window and attach them to the wall beside the window. It is easy to understand that the warp rail is expensive and is difficult to manufacture. Furthermore, the warp rail makes the sashes move in a strange way. It is not good looking.